Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Cardiac dysrhythmia or arrhythmia is a medical condition involving abnormal heartbeat. The term is applied referring to a large group of different diseases affecting the heart. Too fast, too slow or irregular heartbeat is a sign of cardiac dysrhythmia. However, not all arrhythmias are dangerous, some types of disturbed heartbeat are common and do not leave a lasting impact on health. Learn more about arrhythmia, various types of abnormal electrical activities in the heart as well as causes, symptoms and treatments of these conditions.